[NLRS] Parabolic Question

[jcplatt1@mmm.com]

I use a DISH500 offset dish that is 20.5".   Check the internet but you can
buy a new one (less LNA) for $40 to $50 plus shipping.   Here is one site
that has them for $49.99
http://dishdepot.com/Cart/description.php?II=492276&UID=20031110081350192.28.2.17
     I bought mine from some place in Eagan, MN, that Doug, N0NAS, pointed
me to (that I have since forgot).    I think I paid $35 on sale at the
time.

One (possible) advantage with the DISH500 offset dish is that the back
mounting plate appears to be at 90 degrees vertical when the dish is on the
horizon .... I am purely guessing by my thought is that when the dish
designers CADed the design they may have used this back mounting plate
surface as a reference line.  I mounted a simple bubble level flush with
this surface.    This helps alot with figuring out elevation.   Azimuth is
largely right down the feed arm.    After aiming the feed arm and leveling
my bubble, its then a matter of (hopefully) small adjustments ..... once
I've found the signal I peak with azimuth, lock it in, unlock elevation and
peak it then lock it back in, the go back and unlock, peak, and relock
azimuth .... all this can be done in 15 seconds or so.

If you buy this assembly, the little angle mount at the bottom front of the
feed arm that mounts the LNA is not provided so you will have to figure out
where the focal point is.    The website that Donn pointed you towards
contains lots of great information and data including a method to determine
where the feedpoint should be based on physical measurements.   The trick
is to make your feedhorn mount adjustable, do the calculations, mount the
feedhorn where the math says it should go, then show up at one of the NLRS
antenna parties and tweak it.

73, Jon
W0ZQ.